The diagram of the leg shows the femur (1) and tibia (2). The quadriceps muscle
ID: 1356334 • Letter: T
Question
The diagram of the leg shows the femur (1) and tibia (2). The quadriceps muscle (3) applies a force to the lower leg via a tendon (4) that is embedded with the kneecap (5). If the force applied by the muscle to the tendon is FM = 500 N, what is the force of the femur on the kneecap, if the leg is in equilibrium? A simplified model of the leg is shown next to the diagram. The leg bones are represented by two beams attached by a pin. The tendon is modelled by a rope and the kneecap acts like a pulley. The tendon above the kneecap makes an angle ?1 = 66° with respect to the vertical, and the portion of the tendon below the kneecap makes an angle of ?2 = 39° with respect to the vertical. Enter the x component, followed by the y component.
2Explanation / Answer
first let us calculate it along the x direction.
Ffemur = - Fm sin39+ Fm sin66
=-Fm( sin39 + sin66)
= - 771.43 N ( along negative x axis )
along y direction ,
Fm ( cos ( 66) - cos( 39) )
=- 185.204 ( along negative y axis )